“Is there a biblical model for how Christians should think about war?” — Katrina

The Old Testament, of course, is rife with examples of war in which the enemy of God’s people is to be utterly wiped out (Deut. 20:16-18; Josh. 6:17-21). Some debate exists regarding whether or not the Israelite practice of the “ban” (i.e., “dedicated to God for the purpose of utter destruction”) is any way a justification for modern warfare.
We will note here only that ancient Hebrew regulations concerning war represent a step forward from surrounding cultures in which wanton marauding and murder were the norm. Such passages do not serve as evidence of God’s approval or preference for killing (see Ex. 20:13).
The subject is fraught with ambiguities. Argument may be made that Jesus did not forbid the soldier from being a soldier (Matt. 8:5ff; Luke 3:14). He recognized the harsh realities of this broken world with its wars and rumors of war (Matt. 24:6-7).
Simultaneously, war is always an evil. Conflict is the result of human passions (James 4:1-3) and, in its essence, is not compatible with Christian life.
So, there are principles that guide Christian thought in this arena.
Jesus emphasized the principles behind the Law (Matt. 5:21-48), concluding that His followers were to reject hatred and instead love their enemies.
Paul advised Christians to “do the things that make for peace” (Rom. 12:17-19; 14:19).
That Christians believe in and pursue justice, security and freedom means they sometimes must choose the lesser of two evils, having to respond to aggression and horrific injustice with force.
Christians should not glorify war or go to war with gladness and the desire to kill. Christians go to war lamenting the tragedy and grieving over the necessity of killing in order to protect liberty and secure peace.
Bias against war is the ethical norm. Even secular governments should go to war only as a last resort, and only when all other options have been exhausted.
The ultimate goal of all people should be to build a foundation for peace between peoples, cultures and religions so that major war is never considered as a means to an end.